As the natural pressure in a completed oil well gradually depletes, the well may require a means known as artificial lift to continue the flow of petroleum reserves from their subterranean location to the earth's surface. Various forms of artificial lift are known including, for example, gas injection, water injection, and mechanical pumping. Petroleum engineers select a form of artificial lift depending on a number of criteria including, for example, formation geology and economics. The sucker rod pump is a well-known kind of mechanical pump that is widely used in the petroleum industry.
The sucker rod pumping system typically includes a means of providing a reciprocating (up and down) mechanical motion located at the surface near the well head. A string of sucker rods—up to more than a mile in length—is connected to the mechanical means. The sucker rod string is fed through the well tubing down hole where it is connected to the pump. Often the sucker rod string is first connected to the pump apparatus via a top plunger adapter. In a typical pump configuration, the top plunger adapter provides a transition between the sucker rod string and other pump components such as the pump plunger.
As is known in the art, the pump itself includes other components such as two separate valves (a standing valve and a traveling valve), a barrel, and a plunger. Oil is pumped from a well through a series of “downstrokes” and “upstrokes” of the oil pump, which motion is imparted by the above-ground pumping unit. During the upstroke, formation pressure allows the oil to pass through the standing valve and into the barrel of the oil pump. This oil will be held in place between the standing valve and the traveling valve. On the downstroke, the ball in the travelling valve unseats, permitting the oil that has passed through the standing valve to pass therethrough. Also during the downstroke, the ball in the standing valve seats, preventing pumped oil from moving back down into the hole. The process repeats itself again and again, with oil essentially being moved in stages from the hole, to above the standing valve and in the oil pump, to above the traveling valve, through the top plunger adapter, an out of the oil pump, and into the tubing. Oil continues to pass through the tubing to the surface, where the oil is then directed to a storage tank or other such structure.
Presently known top plunger adapters suffer from several shortcomings in various areas of the design. Particularly in wells with large concentrations of sand, silt or debris, known top plunger adapters do not effectively limit the clogging of the sucker rod pump from these materials. It is noted that the top plunger adapter, being uppermost in the pump configuration, is the first component onto which sand or debris present in the tubing falls. Thus, it would be desired to develop a top plunger adapter that lessens pump clogging.
In the typical operation of a sucker rod pump, the pump periodically shuts down for short periods of time up to several hours in length. During this off time, sand that is suspended in the tubing upstream of the pump tends to settle and fall back on the pump components. Thus, it would be desired to provide a top plunger adapter that directs this falling sand into locations so that the pump will not be harmed. Further, on restarting, it would be desired to provide a top plunger adapter that quickly clears the sand and resuspends it in petroleum.
Additionally, in those wells with a high sand concentration, it is likely that siltification or clogging of the pump will occur at some point. Thus, it would be desired that the top plunger adapter provide a self-cleaning mechanism so as to dislodge clogging that does occur.
Hence there has been identified a need to provide improved sand control with a top plunger adapter. It is desired that the top plunger adapter be robust and provide an improved service life over known pumps, and thereby that top plunger provide an improved cost performance for the pump. It would further be desired that the top plunger adapter allow the sucker rod pump provide an improved pumping efficiency. It would also be desired that an improved top plunger adapter be compatible with existing petroleum production devices. The present invention addresses one or more of these needs.